You could pick a theme from a favorite subject of the past year. Other simple craft ideas or just buying ready to paint items from hobby stores like cars or memory boxes. More creative ideas like making masks. I know more preschool age activites than anything else but they might work also..edible finger paints(mix kool-aid powder with corn syrup, or just use pudding) marble painting(place a piece of paper in a container with a lid, such as shoe box or bread crumb container, add alittle paint and marbles then shake to make a pretty picture.

If your have pictures from the past year and old projects they may have done you could help the kids make a scrap book. Fill it with things that they might like to remember from this time in their life, such as favorite memory from kindergarten, what they want to be when they grow up, favorite color etc.